SoundHAB: harmful Chaetoceros event ongoing

[Jack Rensel]

The sun is finally back and a harmful "bloom" (or better, "event") of
Chaetoceros convolutus is occurring today in central Puget Sound where
sampled near Bainbridge Island, especially in Port Blakely.  Kevin Bright
reports concentrations up to 30 cells/ml (30,000 cells/liter) which is more
than sufficient to kill wild or farmed fish after some exposure period, but
so far there are no reports of either.   The extent of C. convolutus events
are very difficult to measure, as the concentrations do not produce obvious
changes in water clarity or water quality parameters like D.O. or pH.
Harmful Chaetoceros are more harmful if the chains are longer as apparently
they wedge more efficiently among the gill lamellae.  Harmful Chaetoceros
cells are often mixed to many tens of meters depth in Puget Sound, such as
occurs periodically in North Hood Canal but not necessarily Dabob Bay where
surface blooms of very high density have been recorded.  The first recorded
fish mortalities with this species were with ling cod in British Columbia
held in pens, but the Strait of Georgia is much more vertically stratified
than most of Puget Sound due to the Fraser Rv. discharge. 

 

Heterosigma blooms were reported again last Friday along the west coast of
Bainbridge Island during an fixed wing aircraft survey by Megan Black, and
we were told that it stretched across the sound toward Seattle.   Sampling
by Liz Tobin at Brownsville Marina ( western side of the channel Bainbridge
Island to Kitsap Peninsula channel) the prior day yielded no cells of the
alga but a mixed community of mostly dinoflagellates, some small flagellates
and a just few diatoms

 

With the sudden hot weather this week, expect the unexpected and please post
your observations or results to SoundHABs.  Tides become larger near the end
of the week, which may help a bit. 

 

I don't mind transcribing reports, but better to have them first hand, so
please share your observations. (!)

 

All prior postings are available in a SoundHAB archive system that may help
HAB scientist begin to understand bloom dynamics in our area.   Otherwise,
there are few records.   

 

If you want to see a real functioning HAB monitoring system, subscribe to
the California habs at sccwrp.org system.  They are building an amazing
database with quantitative postings almost every day from a large area of
the coastline.  However, they don't differentiate Chaetoceros into fish
killers, subgenus Phaeoceros vs. non fish killers, Hyalochaete types, which
is not difficult but useful.  

 

Jack

 

J.E. Jack Rensel Ph.D.

Rensel Associates Aquatic Sciences

cell: 360-631-6538

jackrensel at att.net

 

 

 

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.whoi.edu/pipermail/soundhab/attachments/20100706/ef1ea58c/attachment.htm